DISSERTATION RESEARCH: Evolutionary Physiology of Heat-Shock Gene Expression

University Of Chicago, Chicago IL

Investigators

Abstract

Dissertation Research: Evolutionary Physiology of Heat-Shock Gene Experession Dr. Martin E. Feder & Daniel Lerman The proposed research will investigate a remarkable case in which transposable elements [TEs, pieces of DNA that have the ability to move from one place to another within the genome] have repeatedly but independently disrupted the promoter [region controlling transcription] of a gene encoding an inducible molecular chaperone [a protein that prevents or alleviates damage to other proteins; e.g., Hsp70], which in turn should affect tolerance of environmental stress and fitness. This system has great promise as a model for investigating how large-scale differences in physiological traits arise from minor variation among individuals within populations. Prior research has discovered 3 independent instances in which, in natural populations of the fruit fly Drosophila, TE insertions disrupt the spacing between heat-shock response elements in the hsp70Ba proximal promoter; each such population exhibits distinctive Hsp70 protein levels. For each population, the proposed research will develop replicate lines with which to: (1) Quantify Hsp70 protein levels to test whether flies with TE-disrupted promoters express less Hsp70; (2) Determine whether TE-driven differences in Hsp70 expression affect inducible thermotolerance, a principle organism-level phenotype of Hsp70; (3) Determine, via specific ribonuclease protection assays, whether the TEs disrupt hsp70 transactivation [transcription of the Hsp70-encoding gene]; (4) Measure whether, as predicted, TE-disruption of the hsp70Ba promoter enhances fitness in Drosophila not undergoing heat stress. The proposed research will integrate molecular genetic, biochemical and physiological approaches, and be among the first to elucidate the link between intrapopulation regulatory sequence variation and phenotypic diversification.